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Experiments in Fluids

, Volume 16, Issue 2, pp 73–81 | Cite as

Bluff-body drag reduction by passive ventilation

  • G. K. Suryanarayana
  • Henning Pauer
  • G. E. A. Meier
Originals

Abstract

The drag of a sphere at highRe can be reduced to more than half its value by passive ventilation from the stagnation region to the base. Simultaneously, the flow field around the base is stabilized and made symmetric, leading to reduction of unsteady aerodynamic forces. At highRe, the vent flow breaks through the dead water region associated with the near wake and aerodynamically streamlines the base. The streamlining is done by virtue of a base-vortex-ring beyond the point of turbulent boundary layer separation. A mean flow model for the flow around the vented sphere is proposed.

Smoke flow visualized on a laser light screen placed at two diameters behind the base of the sphere shows the effectiveness of the method in suppressing the flow oscillations.

The drag reduction achieved is very sensitive to the quality of the external surface and relatively insensitive to disturbances in the internal flow. Surface roughness or boundary layer tripping wire on the external flow can completely offset the benefit obtained.

Keywords

Boundary Layer Surface Roughness Smoke Turbulent Boundary Layer Drag Reduction 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • G. K. Suryanarayana
    • 1
  • Henning Pauer
    • 2
  • G. E. A. Meier
    • 2
  1. 1.Experimental Aerodynamics DivisionNational Aerospace LaboratoryBangaloreIndia
  2. 2.DLR Institute for Experimental Fluid MechanicsGoettingenGermany

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